1. Field
The present disclosure relates to vibration signal processing systems and methods, more specifically to rotation speed and/or imbalance tracking for vibratory systems.
2. Description of Related Art
Estimating rotation speed through vibration is an important step in vibration based mechanical diagnostics and prognostics applications. Reliable speed estimation is rudimental to vibration data analysis and algorithmic processing since many failure signatures are highly correlated to the rotation speed, or the fundamental frequency. As the underlying physics of vibration analysis finds the periodic component existing in vibration associated with imbalanced rotation, correct speed estimations will also allow vibration due to imbalance be appropriately pinpointed, measured, and thus minimized with appropriate countermeasures without the need of a tachometer.
While many approaches for estimating fundamental frequency have been developed in various closely related fields, none have been able to give correct results once signal-to-noise ratio (SNR) drops to a certain degree. As implied by the ratio, a drop of SNR includes two potential factors: the increase of noises and the decrease of signals. Conventional or adaptive filters are often used to address the former when noises have known characteristics or are able to be referenced. However, non-stationary noises (e.g., those that emerge and fade out due to sudden changes in external environment) cannot be effectively attenuated. Worsened by the later factor, speed estimations can also become erroneous due to changes of operational conditions internally within systems (e.g., ramping up/down and loading shift). Spurious speed estimations that occur in these transient changes need to be identified and excluded before imbalance and conditions are algorithmically assessed.
Such conventional methods and systems have generally been considered satisfactory for their intended purpose. However, there is still a need in the art for improved speed estimation systems and methods. The present disclosure provides a solution for this need.